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我正在尝试将 JSON 值从 a 序列化serde_json::Map到 SQLite 数据库中。我想在中使用多种数据类型Map并将它们转换为适当的 SQLite 数据类型。

地图在其中创建collect_values并传递给write_record函数。该new_db函数创建一个rustqlite::Connection传递给write_record

但是，当我尝试从地图中插入值时，出现此错误

error[E0277]: the trait bound `serde_json::value::Value: rusqlite::types::to_sql::ToSql` is not satisfied
  --> src/main.rs:51:9
   |
51 | /         params![
52 | |             &values.get("TEST-KEY-1").unwrap_or(&missing_value),
53 | |             &values.get("TEST-KEY-2").unwrap_or(&missing_value)
54 | |         ],
   | |_________^ the trait `rusqlite::types::to_sql::ToSql` is not implemented for `serde_json::value::Value`
   |
   = note: required because of the requirements on the impl of `rusqlite::types::to_sql::ToSql` for `&serde_json::value::Value`
   = note: required because of the requirements on the impl of `rusqlite::types::to_sql::ToSql` for `&&serde_json::value::Value`
   = note: required for the cast to the object type `dyn rusqlite::types::to_sql::ToSql`
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

我需要手动实现序列化器吗？我认为 rusqlite 的types模块已经完成了这项工作。

货运.toml

[package]
name = "sqlite-min-example"
version = "0.1.0"
authors = ["test"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rusqlite = "0.23.1"
serde_json = "1.0"
serde = {version = "1.0.113", default-features = false}

main.rs

use rusqlite::{params, Connection, Result};
use serde_json::json;
use serde_json::map::Map;

fn main() {
    println!("Opening connection");

    let conn = new_db();

    match conn {
        Ok(ctx) => {
            let mp = collect_values();
            let res = insert_record(&mp, &ctx);
        }
        Err(e) => {
            eprintln!("{}", e);
        }
    }
}

pub fn new_db() -> Result<rusqlite::Connection> {
    let conn = Connection::open("test.db")?;
    //let conn = Connection::open_in_memory()?;
    conn.execute(
        "CREATE TABLE IF NOT EXISTS testdb (
            field1 INTEGER,
            field2 INTEGER
        )",
        params![],
    )?;
    // return the new connection context (object)
    Ok(conn)
}

pub fn insert_record(
    values: &serde_json::map::Map<std::string::String, serde_json::value::Value>,
    conn: &rusqlite::Connection,
) -> Result<()> {
    // Insert this if we can't find a value for a key for some reason...
    let missing_value = json!("MISSINGVAL");

    conn.execute(
        "INSERT INTO testdb 
        (
            field1,
            field2
        ) 
            VALUES (
                ?1, ?2
            )",
        params![
            &values.get("TEST-KEY-1").unwrap_or(&missing_value),
            &values.get("TEST-KEY-2").unwrap_or(&missing_value)
        ],
    )?;
    // return any errors that occured
    Ok(())
}

pub fn collect_values() -> serde_json::map::Map<std::string::String, serde_json::value::Value> {
    // Take in the Modbus context and return a map of keys (field names) and their associated values

    let mut map = Map::new();

    map.insert("TEST-KEY-1".to_string(), json!(1234));
    map.insert("TEST-KEY-2".to_string(), json!(5678));

    return map;
}
4

1 回答 1

2

在 Cargo.toml 中为 rusqlite 添加适当的功能：

rusqlite = { version = "0.23.1", features = ["serde_json"] }

也可以看看：

于 2020-06-30T17:14:31.220 回答